Problem Random Quote Machine

Hey guys I’am stuck :pensive:. My random Quote Machine only generates the same Quote over and over again.

My Pen: https://codepen.io/Rosaroterpanther/pen/VWPbYL
the API I use: https://quotesondesign.com/api-v4-0/

I don’t understand why I always get the same result.
My Code:

//getMessage is my Button to generate new Quote, m is my div where i want to place the quote
var btn = document.getElementById("getMessage");
var quoteContainer = document.getElementById("m");
var count = 0;

btn.addEventListener("click", function(){
    $.getJSON("https://quotesondesign.com/wp-json/posts?filter[orderby]=rand&filter[posts_per_page]=1", function(a) {
      addHTML(a);
    });
});

function addHTML(data){
  var curQuote = "";
  curQuote = data[0].content + "<p>&mdash; " + data[0].title + "</p>";
  count++;
  quoteContainer.innerHTML = count + ":" +  curQuote;
}

Solution: